nix-helpers: e23997eec443f8fd6b9a855e0bbebe1f6e587419

     1: { fail, haskellPackages, nixpkgs1803, runCommand, unpack' }:
     2: 
     3: with builtins;
     4: { dir, field }:
     5: import (runCommand "cabal-field-${field}.nix" {
     6:   inherit dir field;
     7:   buildInputs = [ fail ];
     8: } ''
     9:   set   -e
    10:   set   -o pipefail
    11:   shopt -s nullglob
    12: 
    13:   cd "$dir" || fail "Couldn't cd to '$dir'"
    14: 
    15:   VAL=""
    16:   for F in *.cabal
    17:   do
    18:     LINES=$(grep -i "^$field\s*:" < "$F") ||
    19:       fail "No '$field' lines in '$F'"
    20: 
    21:     VAL=$(echo "$LINES" | head -n1       |
    22:                           cut -d ':' -f2 |
    23:                           sed -e 's/\s//g')
    24:   done
    25:   [[ -n "$VAL" ]] || {
    26:     echo "Couldn't find Cabal field '$field' in '$dir'" 1>&2
    27:     exit 1
    28:   }
    29:   echo "\"$VAL\"" > "$out"
    30: '')